You've seen plenty of pictures of the Orion Nebula, but most of them (like this one) have been taken in visible light.
Image Copyright: Robert Gendler
You can see hot, blue stars, and the glow from gas which is excited by the radiation from those stars. Astronomers call this cloud of ionized hydrogen an HII region. This particular HII region in Orion is sometimes called "Messier 42", or "M42", since it was the 42nd item listed in Charles Messier's catalog of non-stellar objects in the sky. The glowing gas cloud occupies only a small fraction of the entire constellation in the visible; it's the "sword" hanging from Orion's belt.
Image Copyright: Matthew Spinelli
But there's more to the Orion Nebula than meets the eye -- literally. If you look at other wavelengths, you'll find evidence for gas and dust extending far beyond the visible extent.
Your job: make pictures of an area of the sky, 15 degrees by 15 degrees (just a bit smaller than the entire constellation), centered on the visible cloud of glowing gas. Use the SkyView Advanced Form to reveal how this region appears when viewed at different wavelengths of electromagnetic radiation. Then interpret those pictures to explain just what sort of material can be found in this part of the sky.
Infrared: IRAS 100 micron Radio: CO (carbon monoxide) Radio: 1420 MHz Bonn (21-cm radio waves) X-ray: RASS Cnt Broad
You should have 5 pieces of paper, each showing the same region of the sky in Orion, but at a different wavelength. Now, make a hardcopy of the optical picture by Matthew Spinelli, above. It shows a slightly larger area of the sky than all the others, but you should be able to match it up; concentrate on the brightest sections of the nebulosity and on the three stars in the "belt" of Orion.
Write a brief explanation of what each of these 6 pictures tells us. Be sure to mention what is emitting the light in each case.
The entire complex of material is roughly 1500 light years away from the Earth. Look at the IRAS 100 micron image. Draw on this image a circle which you think encompasses most of the material. Use the grid on the picture to estimate the diameter of this circle in degrees. Calculate the approximate size of the Orion cloud complex, in light years.
Copyright © Michael Richmond. This work is licensed under a Creative Commons License.